Door handle with means for reducing ultra-high-frequency communication radiation

Abstract

A handle for a motor vehicle opening, equipped with an ultra-high-frequency antenna having a device for transmitting and receiving a signal at a predetermined wavelength, with a device for detecting the approach of and/or contact by a user, with a printed circuit board and with at least one connecting cable intended for electrically connecting the printed circuit board to an electronic control unit. The at least one connecting cable has a section either projecting from the remainder of the at least one connecting cable or surrounded by an electromagnetically insulating coating coaxial with the at least one connecting cable, a length of the projecting section or a length of the coaxial coating being equal to one quarter of said predetermined wavelength with a tolerance of +/−20%.

Claims

1. A handle for a motor vehicle opening, equipped with an ultra-high-frequency antenna for transmitting and receiving a signal at a predetermined wavelength, with a device for detecting the approach of and/or contact by a user, with a printed circuit board and with at least one connecting cable intended for electrically connecting the printed circuit board to an electronic control unit of the motor vehicle, said at least one connecting cable having a section projecting from the remainder of said at least one connecting cable, a length of the projecting section being equal to one quarter of said predetermined wavelength with a tolerance of +/−20%, wherein the section projecting from the remainder of said at least one connecting cable extends at 90° with a range of variation of +/−30° around this value compared to the remainder of said at least one connecting cable, the projecting section forming a loop to reduce electromagnetic radiation from said at least one connecting cable oriented inside the motor vehicle.

2. The handle as claimed in claim 1, wherein the loop has two branches flattened against each other or two branches having a spacing between them of less than one fifth of the predetermined wavelength with a tolerance of +/−20%.

3. The handle as claimed in claim 1, wherein the section projecting from the remainder of said at least one connecting cable is located in a first quarter of the length of said at least one connecting cable starting from the printed circuit board.

4. The handle as claimed in claim 1, wherein said at least one cable comprises a part in the form of a microstrip extending against a face of the printed circuit board, the microstrip incorporating the section projecting from the remainder of said at least one connecting cable.

5. The handle as claimed in claim 1, wherein the ultra-high-frequency antenna, the device for detecting the approach of and/or contact by a user and the printed circuit board are housed in a sealed casing, the sealed casing and the handle comprising a passage respectively toward the outside of the casing and the outside of the handle for said at least one connecting cable.

6. A motor vehicle opening comprising a handle on an outer face, the opening comprising an automatic locking and unlocking device, wherein the handle is as claimed in claim 1, said at least one connecting cable passing through the opening, the section of said at least one connecting cable being located inside the opening toward its inner face opposite to its outer face or being housed in the handle.

7. An assembly of an electronic control unit responsible for locking and unlocking at least one opening of a motor vehicle and at least one opening, wherein the opening is as claimed in claim 6, said at least one connecting cable connecting the printed circuit board to the electronic control unit, the automatic locking and unlocking device of the opening being controlled by the electronic control unit.

8. A motor vehicle, an assembly as claimed in claim 7.

9. The handle as claimed in claim 3, wherein the loop has two branches flattened against each other or two branches having a spacing between them of less than one fifth of the predetermined wavelength with a tolerance of +/−20%.

10. The handle as claimed in claim 2, wherein the section projecting from the remainder of said at least one connecting cable is located in a first quarter of the length of said at least one connecting cable starting from the printed circuit board.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features, aims and advantages of aspects of the present invention will become apparent from reading the detailed description that follows and from examining the appended drawings given by way of non-limiting examples, and in which:

(2) FIG. 1 is a schematic representation of a sectional view of a motor vehicle door having a handle equipped with an ultra-high-frequency antenna, with means for transmitting and receiving a signal at a predetermined wavelength and its internal interconnection to the motor vehicle according to the prior art,

(3) FIG. 2 is a schematic representation of a sectional view of a motor vehicle door having a handle equipped with an ultra-high-frequency antenna, with means for transmitting and receiving a signal at a predetermined wavelength and its internal interconnection to the motor vehicle according to a first embodiment of the present invention, the interconnection comprising a quarter-wave line limiting radiation of electromagnetic waves inside the vehicle,

(4) FIG. 3A is a schematic representation of a sectional view of a printed circuit board, an ultra-high-frequency antenna and an interconnection according to the first embodiment, comprising a quarter-wave line in accordance with the present invention,

(5) FIG. 3B shows a schematic representation of a perspective view of a circuit board supporting on one face a part of the interconnection in the form of a microstrip having a quarter-wave line as an alternative embodiment according to the present invention to the embodiment shown in FIGS. 2 and 3A,

(6) FIG. 3C is a schematic representation of a perspective view of an interconnection section surrounded by an electromagnetically insulating coating according to a second embodiment of an interconnection according to the present invention, the coating representing an alternative to the quarter-wave line shown in FIG. 2, FIG. 3A and FIG. 3B,

(7) FIG. 4A shows the radiation obtained by a handle according to the prior art,

(8) FIG. 4B shows a handle according to an aspect of the present invention with an interconnection having a quarter-wave line or an electromagnetically insulating coating, the radiation in FIG. 4B according to an aspect of the present invention being limited toward the inside compared to the radiation of FIG. 4A obtained by a handle according to the prior art,

(9) FIG. 5 shows three radiation curves around the handle according to the printed circuit board and ultra-high-frequency antenna assemblies, which are respectively obtained by a handle without interconnection, a handle according to the prior art with interconnection but without a quarter-wave line or insulating coating and a handle according to an aspect of the present invention,

(10) FIG. 6 is a schematic representation of a top view of a motor vehicle, certain openings of which are provided with handles equipped with a device for detecting a locking/unlocking intention with an interconnection to an electronic control unit according to an aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(11) Referring particularly to FIG. 1, FIG. 2, FIGS. 3a-3C and FIG. 6 and particularly comparing FIG. 1 with FIG. 2, an aspect of the present invention relates to a handle 6 for a motor vehicle opening 8. The opening can be a door 8 of the motor vehicle.

(12) The handle 6 of the opening 8, for detecting an intention to lock/unlock, as mentioned above, is equipped with an ultra-high-frequency antenna 2 having means for transmitting and receiving a signal at a predetermined wavelength λ. It is known that an electromagnetic wave propagates in a vacuum, at a constant and unsurpassable speed. The wavelength λ can be defined as a function of the frequency f of the electromagnetic wave and the speed of light c by:
λ=c/f  [Math. 1]

(13) The handle 6 of the opening 8 is thus equipped with a device for detecting the approach of and/or contact by a user, a printed circuit board 3 and at least one connecting cable 7, also referred to as interconnection, intended for electrically connecting the printed circuit board 3 to an electronic control unit referenced 15 in FIG. 6. There can in fact be one connecting cable 7 or multiple connecting cables 7, then being in the form of a bundle of cables.

(14) This electronic control unit 15 can be a box referred to as a BCM box also controlling central electronics, an alarm system, the indicators, the hazard lights, the window lifts, the rear window and the heated rear-view mirrors, the interior lighting and the windshield wipers of the motor vehicle.

(15) These features are common to a handle 6 according to the prior art and to a handle 6 according to all embodiments of the present invention.

(16) According to an aspect of the present invention, said at least one connecting cable 7 has a section 9, 9a that carries an element or a shape making it possible to limit the electromagnetic radiation toward the inside of the motor vehicle. In the case of multiple connecting cables 7, at least one cable 7 can carry such a section 9, 9a or this section 9, 9a can be carried by multiple connecting cables 7, for example by all the cables 7.

(17) In a first embodiment of the present invention, as shown in FIG. 2, FIG. 3A and FIG. 3B, the section 9 projects from the remainder of said at least one connecting cable 7. A length of the projecting section 9 is predetermined to be equal to one quarter of said predetermined wavelength λ, this with a tolerance of +/−20% around this wavelength value.

(18) In a second embodiment of the present invention, as shown in FIG. 3C, the section 9a is surrounded by an electromagnetically insulating coating 16 coaxial with said at least one connecting cable 7. A length of the section 9a surrounded by the coaxial coating 16 is then equal to one quarter of said predetermined wavelength λ, this with a tolerance of +/−20% around this wavelength value.

(19) Such a section 9 according to the first embodiment is frequently referred to by the name λ/4 stub or quarter-wave line. Likewise, such a section 9a surrounded or enveloped by an electromagnetically insulating coating 16 according to the second embodiment is frequently referred to by the name “bazooka balun” or coated section. The use of such means has been known for resolving issues concerning impedance but not emitted radiation.

(20) The technical effect obtained by an aspect of the present invention can be seen by comparing FIG. 1 and FIG. 2. In FIG. 1, the radiation directed toward the outside and the radiation directed toward the inside are respectively symbolized by ovals 1a, 1be and 1b. In FIG. 1, the inner 1be and outer 1a ovals are of substantially the same size while the inner oval 1b of FIG. 2 for a handle 6 according to an aspect of the invention is smaller than the inner oval 1e of FIG. 1.

(21) It should be considered that the ovals 1a, 1be, 1b define the radiation very schematically and that there is radiation outside the ovals 1a, 1be, 1b, the radiation substantially forming a ring around the handle 6.

(22) The second step was to identify that this unwanted radiation directed toward the inside is caused by the cable or cables 7 of the interconnection connecting the printed circuit board 3 to the electronic control unit 15.

(23) Several models were then developed producing the radiation referenced in FIG. 5 so as to better identify unwanted radiation and to see if the solution proposed by an aspect of the present invention was effective.

(24) Referring to FIG. 1, FIG. 2, FIG. 3C, FIG. 4A, FIG. 4B and FIG. 5 for references, the first model A consisted of a printed circuit board 3 and an ultra-high-frequency antenna 2 forming a first assembly without interconnection. In the ring of radiation surrounding the first assembly, the rear part oriented inside the vehicle is not very large. The reason is that, for this model A, the thickness of the opening is sufficient to limit the radiation toward the inside of the vehicle.

(25) The second model B consisted of a printed circuit board 3 and an ultra-high-frequency antenna 2 forming a second assembly with interconnection, because the cable or cables 7 connecting the assembly to an electronic control unit 15 are present for this second model.

(26) In the ring of radiation surrounding the second model B, analogous to the radiation shown in FIG. 4A, the rear part Ret of the radiation oriented inside the vehicle is significantly increased compared to the ring of the first assembly and is large, this being able to be due only to the presence of the interconnection, therefore of the cable or cables 7.

(27) The third model C is in accordance with an aspect of the present invention and consisted of a printed circuit board 3, an ultra-high-frequency antenna 2 forming a third model with interconnection, but the cable or cables 7 connecting the printed circuit board of the third model C to an electronic control unit have a quarter-wave line or a section 9a covered by being surrounded by an electromagnetically insulating coating 16.

(28) It can be seen in FIG. 4B that in the radiation released by such a third model C, the rear part Rinv of the radiation oriented inside the vehicle is significantly reduced compared to the rear part Ret of the ring of the second model B and is substantially equivalent to that of the first model A, which shows that the presence of a quarter-wave line or of a covered section 9a in the interconnection reduces the radiation of electromagnetic waves toward the inside of the motor vehicle, this being the desired goal.

(29) FIG. 4A and FIG. 4B therefore respectively show a 3D radiation pattern for a handle 6 according to the prior art and a handle 6 according to an aspect of the present invention, respectively. In these two figures, the angles define the direction of the radiation, a radiation toward angles close to 180°, by being between −130° and +130°, being a radiation directed toward the inside of the vehicle.

(30) FIG. 4A shows increased radiation Ret toward the inside of the door 8 caused by the electrical connecting cable or cables 7 compared to the radiation Rinv toward the inside for a handle 6 according to an aspect of the present invention shown in FIG. 4b.

(31) FIG. 3A shows a non-limiting embodiment of the invention of a section 9 having a length equal to one quarter of said predetermined wavelength λ. This section 9 or quarter-wave line extends at 90° with a range of variation of +/−30° around this value compared to the remainder of said at least one connecting cable 7, the section 9 forming a loop.

(32) This is shown with a minimum of electronic elements, namely a printed circuit board 3 and an ultra-high-frequency antenna 2 having means for transmitting and receiving a signal at a predetermined wavelength λ, therefore without a device for detecting the approach of and/or contact by a user or a casing 5.

(33) In FIG. 2, the loop 9 can define a space with respect to its two branches. The two branches can have a maximum spacing between them of less than one fifth of the predetermined wavelength with a tolerance of +/−20% around this value.

(34) Conversely, in FIG. 3A, the loop 9 has two branches flattened against each other. In both cases, the quarter-wave line loop consists of a round trip by at least one connecting cable 7 over a distance equal to one quarter of the wavelength λ of the transmitted or received signal.

(35) In FIG. 3A, the quarter-wave line loop is positioned as being adjacent to the printed circuit board 3 comprising the ultra-high-frequency antenna, this not being limiting. The quarter-wave line loop can in fact be positioned differently on said at least one electrical cable 7. For example, the section 9 projecting from the remainder of said at least one connecting cable 7 can be located in a first quarter of the length of said at least one connecting cable 7 starting from the printed circuit board 3.

(36) FIG. 3B shows a first sub-embodiment that is an alternative to the first embodiment. In this first sub-embodiment, the connecting cable or cables 7 can comprise a part in the form of a microstrip 7a extending against one face of the printed circuit board 3. The microstrip 7a then incorporates the section 9 projecting from the remainder of said at least one connecting cable 7, this projecting section 9 being of a length equal to one quarter of the wavelength λ of the wave signal of the transmitted or received signal.

(37) In FIG. 3B, the printed circuit board 3 is of parallelepipedal shape and has a thickness h. The printed circuit board 3 carries the microstrip 7a on one of its largest faces, while the microstrip 7a has a length L and a width W. The projecting section 9 is located halfway along the microstrip 7a, this not being limiting.

(38) In FIG. 3C, for the second embodiment of the present invention, a metal sleeve 16 is shown as the electromagnetically insulating coating. The metal sleeve 16 advantageously covers or envelops the section 9a at a distance. This metal sleeve 16 can be positioned anywhere along the length of a connecting cable 7. It is the length of the covered section 9a that is equal to one quarter of the wavelength λ of the transmitted or received signal.

(39) FIG. 5 shows three radiation curves as a function of a positioning around the door that is quantified in terms of angle between −180° and +180° for, respectively, the first model A, which has squares, the second model B according to prior art, which has circles, and the third model C according to an aspect of the present invention, which has no respective sign, these three models having been explained above. The angles of the rear radiation for FIGS. 4A and 4B were between −130° and +130°, while the angles of the rear radiation for FIG. 5 are between −50° and +50°.

(40) For an angle of 50°, the curve for the second model B according to the prior art with interconnection shows a strong radiation amplitude of about 3 dBi, while the curve for the third model C according to an aspect of the present invention shows an amplitude similar to that of the curve for the first model A without interconnection of −4 dBi and −7 dBi, respectively.

(41) This applies to the angle range between −50° and +50°, for which the radiation of the second assembly is stronger than the radiation of the first and third assemblies.

(42) As particularly clearly visible in FIG. 2, the ultra-high-frequency antenna 2, the device for detecting the approach of and/or contact by a user and the printed circuit board 3 can be housed in a sealed casing 5. This applies to the microstrip 7a when this microstrip 7a is present and is applied against one face of the printed circuit board 3.

(43) In this case, the sealed casing 5 and the handle 6 can comprise a passage respectively toward the outside of the casing 5 and the outside of the handle 6 for the remainder of said at least one connecting cable 7.

(44) Referring more particularly to FIG. 6, an aspect of the present invention relates to an opening 8 of a motor vehicle 14 comprising a handle 6 on a face referred to as outer face, the opening 8 comprising automatic locking and unlocking means, the handle 6 being as described above.

(45) The connecting cable or cables 7 pass through the opening 8, the section 9 projecting from the remainder of said at least one connecting cable 7 or the section 9a coated with an electromagnetically insulating coating 16, advantageously a sleeve, being located inside the opening 8 toward its inner face opposite to its outer face or in the handle 6.

(46) The connecting cables 7 are directed toward an electronic control unit 15 incorporated in the motor vehicle 14 and located substantially in the middle zone of the motor vehicle so as to be approximately at an equal distance from all the handles, opening and closing of which are controlled remotely, this possibly also not being the case.

(47) FIG. 6 merely shows, for each connecting cable 7, projecting sections 9 having a length equal to one quarter of said predetermined wavelength λ, that is to say according to the first embodiment of the present invention, but the alternative of the first embodiment and the second embodiment having a covered section 9a can also be implemented.

(48) As shown in FIG. 6, an aspect of the present invention relates to an assembly of an electronic control unit 15 responsible for locking and unlocking at least one opening 8 of a motor vehicle 14 and at least one opening 8 as described above.

(49) The connecting cable or cables 7 connect the printed circuit board 3 inside each handle 6 to the electronic control unit 15 located at a distance from each handle 6. The means for automatically locking and unlocking the opening 8 are controlled by activation means of the electronic control unit 15. An aspect of the present invention relates finally to a motor vehicle 14 comprising such an assembly described above.

(50) FIG. 6 shows a motor vehicle 14 comprising three handles 6 for an opening 8 including two handles 6 for a front door 8 and one handle 6 for a rear trunk. One or more connecting cables 7 connect each printed circuit board 3 inside each handle 6 to an electronic control unit 15.